Works fine on floor vents. must be trimmed in carpeted areas. So far, so good.

The MVCX512 Magnetic Vent Covers are a bit of a joke. The magnetic force is so weak that not only will they not stay put when the air is blowing, they tend to curl and fall off even when put on any old flat piece of metal. The only reason I'm giving them 2 stars is that they are the right size and shape and sturdy enough to act as a vent cover when taped in place with duct tape.

This product does not have strong enough magnetic force to hold the weight of the vent cover against gravity. I have sheet steel A/C vents. The covers barely hold on to the wall vents and don't hold at all to the ceiling vents. When the A/C fan came on, the wall cover fell to the floor. I compared the magnetic strength of the vent covers with photo magnets from Shutterfly by applying the vent cover to the refrigerator. They both held with the same apparent strength. I tried to attach the photo magnets to the wall vent. It held, but not as strongly as to the refrigerator. The problem seems to be the amount of ferrous material in the vent cover and the shape of the cover - mine were stamped by machine and the built-in air deflectors in the vent are raised slightly from the edges of the vent where they attach to the wall/ceiling. There isn't enough flat surface for the magnetic covers to grip. MVCX512 Magnetic Vent Covers (5" X 12", 3-pk)

These magnetic vent covers do the job, but they need more magnet to them, they don't stay in place.Other than that they are just fine.

The product works well but in the picture it appears to be black/dark brown. When I received it they were white. The company claims they do not come in the darker color. The white did not work for me. They refunded me 100% of the money.